Water chemistry and sporulation by aquatic hyphomycetes

Abstract

Maple leaf disks were exposed in a softwater stream for two weeks and then aerated for 2 d in water to induce spore production by aquatic hyphomycetes. Sporulation was inhibited by the addition of yeast extract or leaf leachate (up to 2·5 g l⁻¹) to the sporulation water. With leaf leachate, but not with yeast extract, this effect was neutralized by the addition of 50 mg l⁻¹ of CaCl₂. Sporulation increased at intermediate concentrations of several inorganic compounds (CaCl₂; KH₂PO₄/K₂HPO₄; NaNO₃; NaCl). It increased at low concentrations (1–3 g l⁻¹) of an artificial seasalt mixture, was much reduced at 7·5 g l⁻¹ and absent at 15 g l⁻¹.